Rehabilitating pipe segment and existing pipe rehabilitation method using same

ABSTRACT

A rehabilitating pipe segment comprises first and second segment halves linked together to provide a variable-width segment. The first segment half has an internal surface plate, a convex plate extending parallel to the internal surface plate, and a side plate extending perpendicular to the internal surface plate. The second segment half has an internal surface plate, an internal plate extending parallel to the internal surface plate and forming a concavity, and a side plate extending perpendicular to the internal surface plate. The convex plate and a braking rubber are fitted into the concavity to link the first and second segment halves together to provide the variable-width segment. When tension of a specified amount or greater acts on the variable-width segment, the first and second segment halves move relative to each other in the pipe length direction against the braking force of the braking rubber.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rehabilitating pipe segment adaptedfor use to rehabilitate existing pipes by linking a plurality ofsegments in the circumferential direction and pipe length direction, andto a rehabilitation method using this segment to rehabilitate existingpipes.

2. Description of the Related Art

There are pipe rehabilitation methods known in the art for linking aplurality of segments in the circumferential direction and pipe lengthdirection to assemble a rehabilitating pipe when sewerage pipes,waterworks pipes, agricultural water pipes, and other existing pipeshave aged. A filler is used to fill the space between the rehabilitatingpipe and existing pipe so as to integrate both the pipes together andconstruct a composite pipe (JP-A-2003-286742 and JP-A-2005-299711).

The rehabilitating pipe segment is an assembly unit for a rehabilitatingpipe and comprises an internal surface plate, side plates, and endplates, these plates being integrally molded from a transparent ornontransparent plastic material in the form of a block. Reinforcingplates and ribs are preferably provided to increase the strength of thesegment.

SUMMARY OF THE INVENTION

The existing pipe described above is formed by connecting a plurality ofpipes of a specified length, and the seams in the existing pipetherefore occasionally separate when an earthquake or some other greatforce acts on the exterior. In cases in which the existing pipe has beenrehabilitated using the segments described above, the seam portions orportions in the vicinities of the seams will rupture under the tensionin the rehabilitating pipe integrated with the existing pipe. This isbecause the width dimension of the segment constituting therehabilitating pipe is fixed and cannot be expanded or contracted bytension. In the case that the existing pipe is a sewerage pipe, externalliquefied sediment flows in through ruptured portions of the seweragepipe between separated seams of the sewerage pipe, compromising thefunction of the sewerage pipe.

When a curved existing pipe is being rehabilitated, the segment requiresspecial machining as well, such as cutting the segment at a slant inrelation to the curve, and there have been problems in that the curvedrehabilitating pipe cannot be assembled in a simple manner.

It is therefore an object of the present invention to provide arehabilitating pipe segment that makes it possible both to construct acomposite pipe that suffers no functional loss even when a large impactacts externally and to rehabilitate even a curved existing pipe in asimple manner; and also to provide an existing pipe rehabilitationmethod using this segment.

The present invention provides a rehabilitating pipe segment adapted foruse to assemble a rehabilitating pipe inside an existing pipe, therehabilitating pipe having a smaller outside diameter than the insidediameter of the existing pipe. The rehabilitating pipe segment iscomposed of a first segment half and a second segment half, which arecapable of moving relative to each other in the pipe length direction tomake the width of the segment of the first and second segment halvesvariable in the pipe length direction.

In the segment of the present invention, the pipe-length-direction widthof the segment composed of the first and second segment halves increaseswhen tension of a predetermined value or greater is applied in the widthdirection corresponding to the pipe length direction of therehabilitating pipe.

The first segment half has an internal surface plate constituting theinternal peripheral surface of the segment, a convex plate extendingparallel to the internal surface plate, and a side plate extendingperpendicular to the internal surface plate and constituting one sideplate of the segment. The second segment half has an internal surfaceplate constituting the internal peripheral surface of the segment, aninternal plate for forming a concavity, the internal plate extendingparallel to the internal surface plate, and the other side plate of thesegment extending perpendicular to the internal surface plate. Theconvex plate of the first segment half and a braking member for brakingthe first and second segment halves from separating are fitted into theconcavity of the second segment half so as to link the first and secondsegment halves together.

In the present invention, a rehabilitating pipe segment that does notuse the braking member is also proposed.

A rehabilitation method for rehabilitating an existing pipe comprisesthe steps of linking first and second segment halves together to providea variable-width segment whose width in the pipe length direction isvariable; linking the variable-width segments together in thecircumferential direction to provide a first pipe unit; linkingfixed-width segments together in the circumferential direction toprovide a second pipe unit; and linking the first and second pipe unitstogether in the pipe length direction so as to assemble a rehabilitatingpipe inside an existing pipe.

The first pipe units are preferably disposed at the seam portions of theexisting pipe or in the vicinities thereof.

Alternatively, the first pipe units are disposed at the curved portionsof the existing pipe, and the widths of the variable-width segmentsconstituting the first pipe units increase progressively from one end tothe other end in the circumferential direction so as to be at a minimumin the internal periphery of the curved portions and a maximum in theexternal periphery of the curved portions.

The width dimensions in the rehabilitating pipe segment of the presentinvention increase when tension of a specific value or greater acts inthe width direction corresponding to the pipe length direction of therehabilitating pipe. This allows pipe earthquake resistance to beimproved when a rehabilitating pipe is assembled using therehabilitating pipe segment of the present invention. A curvedrehabilitating pipe can also be assembled in a simple manner using therehabilitating pipe segment of the present invention.

Specifically, if an earthquake or some other severe external shockoccurs and tension acts on the pipe so as to separate the seams of theexisting pipe, width varies accordingly in the rehabilitating pipesegments disposed at the seams, thereby preventing the rehabilitatingpipe from rupturing.

The width in the pipe length direction can be varied in therehabilitating pipe segment of the present invention. Therefore, therehabilitating pipe can be curved merely by adjusting the width of thesegment, requiring no special machining of the segment. This enables acurved rehabilitating pipe to be assembled in a simple manner and in ashort amount of time. Increases in the width of the rehabilitating pipesegment also prevent ruptures in the rehabilitating pipe even if tensionacts in the increased width portions.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and followingdetailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the structure of a fixed-widthsegment used to assemble a rehabilitating pipe;

FIG. 2 is a cross-sectional view along the line A-A in FIG. 1, showingthe structure of two segments linked together in the circumferentialdirection;

FIG. 3 is a perspective view showing a state in which segments have beenlinked together in the circumferential direction so as to assemble apipe unit;

FIG. 4 is a segment top view showing a state in which segments have beenlinked together in the pipe length direction;

FIGS. 5 a through 5 f are illustrative views showing a method forlinking segments together in the pipe length direction;

FIGS. 6 a through 6 c are cross-sectional views showing the structure ofa variable-width segment;

FIG. 6 d is an end surface view showing the end surface of thevariable-width segment;

FIGS. 7 a and 7 b are enlarged views of areas a and b, respectively, inFIG. 6;

FIG. 8 is a cross-sectional view showing the arrangement and linkingstructure in the pipe length direction of a variable-width segment in arehabilitating pipe inside an existing pipe;

FIG. 9 is a cross-sectional view showing the arrangement of avariable-width segment in a rehabilitating pipe inside an existing pipe;

FIG. 10 is a cross-sectional view along the line A-A in FIG. 9;

FIG. 11 is a cross-sectional view showing the state of a variable-widthsegment when the seams of an existing pipe have separated due to anearthquake;

FIG. 12 a is a cross-sectional view showing the cross-sectional shapeand dimensions of a braking rubber;

FIG. 12 b is an enlarged view of area d in FIG. 11;

FIG. 13 is a cross-sectional view of a rehabilitating pipe when a curvedrehabilitating pipe is assembled using variable-width segments;

FIGS. 14 a and 14 b are enlarged views of areas e and f, respectively,in FIG. 13;

FIGS. 15 a through c are cross-sectional views showing the structure andassembly of another embodiment of a variable-width segment;

FIG. 15 d is an end surface view showing the end surface of thevariable-width segment;

FIGS. 16 a through 16 c are cross-sectional views showing the structureand assembly of still another embodiment of a variable-width segment;

FIG. 16 d is an end surface view showing the end surface of thevariable-width segment;

FIG. 17 is a cross-sectional view of a rehabilitating pipe when a curvedrehabilitating pipe is assembled using the variable-width segment inFIG. 16; and

FIG. 18 is a segmented perspective view showing a state in which arehabilitating pipe is assembled inside an existing pipe usingfixed-width segments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are described in detail hereinafterwith reference to the attached drawings. The rehabilitating pipe segmentof the present invention is used as a segment'for rehabilitating asewerage pipe, a waterworks pipe, an agricultural water pipe, or someother existing pipe, and an existing pipe is rehabilitated using thisrehabilitating pipe segment.

FIG. 1 shows the structure of a rehabilitating pipe segment 1(hereinafter referred to simply as a segment), which is used as anassembly unit of a rehabilitating pipe for rehabilitating an existingpipe. The segment 1 is an integrally molded block-shaped member made ofa plastic material and composed of an internal surface plate 101constituting the internal peripheral surface of the rehabilitating pipe,side plates 102, 103 erected vertically at both sides extending in thecircumferential direction of the internal surface plate 101, and endplates 104, 105 erected vertically at both ends extending in the pipelength direction of the internal surface plate 101. The side plates 102,103 and end plates 104, 105 are on four sides at the same height andconstitute outer wall plates surrounding the peripheral edges of theinternal surface plate 101. In the present embodiment, the segment 1 hasa shape curved into an arc obtained by dividing the circumference into,e.g., five equal parts at predetermined angles) (72°). The segment isnot limited to an arc or fan shape, and can also be a rectangularparallelepiped, a curved shape made by providing roundness to rightangles, or another shape in accordance with the cross-sectional shape ofthe existing pipe, the size thereof, or the maintenance locations of theexisting pipe.

In cases of reinforcing the mechanical strength of the segment 1, aplurality of internal plates 106, 107 similar to the side plates 102,103 are erected on the top surface of the internal surface plate 101inside of the side plates 102, 103. On the inside surfaces of the sideplates 102, 103 and on both side surfaces of the internal plates 106,107 are formed convex plates 103 b, 106 b, 107 b projecting to the sidesat a plurality of locations in order to prevent deformation, creating arib structure and increasing the strength of the segment 1.

The internal surface plate 101, the side plates 102, 103, the end plates104, 105, the internal plates 106, 107, and the convex plates are allmade of the same transparent, semitransparent, or nontransparentplastic, and are integrally molded using a conventional moldingtechnique.

A plurality of openings 101 a for linking segments 1 in thecircumferential direction are formed at both ends of the internalsurface plate 101, and in order to link the segments 1 in the pipelength direction, a plurality of holes 102 a, 103 a, and 106 a areformed in the side plates 102, 103 and internal plate 106, and aplurality of grooves 107 a are formed in the internal plates 107.

Bolts 6 are inserted into insertion holes 104 a, 105 a from the openings101 a of the segments 1, and nuts 7 are threaded over the bolts 6 inorder to fasten the end plates 104, 105 together and link the segments 1in the circumferential direction, as shown in FIG. 2. Concavities 104 b,104 c are formed across the entire lengths of the end plates 104 in thepipe length direction, and convexities 105 b, 105 c which fit into theconcavities are similarly formed in the end plates 105. Therefore, theoperation of positioning and firmly connecting the segments 1 whenlinking them together is made easier. The watertightness of the linkedportions can be increased by coating the fitted portions with a sealmaterial (not shown). After the segments are finished being linked, theopenings 101 a are closed using lids (not shown) or other means. Theinternal surfaces of the lids at this time are continuous with theinternal surfaces of each internal surface plate 101 so as to form aneven internal surface. In cases in which it is easy to link the segmentsin the circumferential direction by the bolts 6 and nuts 7, there is noparticular need for the openings 101 a. Two sets of bolts and nuts areused in FIG. 2, but in the case of segments used for small-diameterexisting pipes, the segments can be linked in the circumferentialdirection by only one set of a bolt and nut.

When segments 1 are linked sequentially in the circumferential directionto complete a full circle, a closed ring-shaped short pipe 10(hereinafter referred to as a pipe unit) of a predetermined short lengthcan be assembled, such as is shown in FIG. 3. The pipe unit 10 has ashape obtained when a circular pipe is cut into rings of a predeterminedwidth D perpendicular to the pipe length direction X, and the outsidediameter thereof is a value slightly less than the inside diameter ofthe existing pipe to be rehabilitated. The segments 1 correspond tomembers obtained when the pipe unit 10 is cut in the diametral directionR and divided (preferably equally divided) into a plurality of units inthe circumferential direction.

The internal surface plates 101, side plates 102, 103, and end plates104, 105 are shown in FIG. 3 as primary structural members of thesegments 1, and the internal plates 106, 107, convex plates, and otherreinforcing structures are not shown for the sake of avoidingcomplexity. In this Specification, the term “pipe length direction”refers to the direction indicated by the arrow X extending in the pipelength direction of the pipe unit 10 in FIG. 3, the term “diametraldirection” refers to the radial direction indicated by the arrow Rpointing toward the center axis of the pipe unit 10, and the term“circumferential direction” refers to the circumferential direction ofthe circle formed by the pipe unit 10.

In the work of rehabilitating the existing pipe, first, a plurality ofsegments 1 are linked in the circumferential direction inside theexisting pipe as described above so as to assemble the pipe unit 10, andthe segments of the pipe unit 10 are linked in the pipe length directionso as to assemble a rehabilitating pipe.

FIGS. 4 and 5 show segments as being linked in the pipe length directionusing nuts 12 and rod-shaped screw members 11 having screws 11 a, 11 bformed at both ends. The nuts 12 are shaped so as to be capable ofpassing through the holes 102 a, 103 a in the side plates 102, 103 ofthe segments 1, but not through the holes 106 a in the internal plates106. Flanges 14 a of nuts 14 threaded over the screws 11 a of the screwmembers 11 are sized so as to be capable of passing through the holes102 a in the side plates 102 of the segments 1, but not through theholes 106 a in the internal plates 106. Flanges 13 b of bolts 13threaded over the nuts 12 have larger diameters than the holes 106 a inthe internal plates 106, and the diameters of the screw members 11 aresmaller than the diameters of the holes 106 a in the internal plates106.

A nut 12 is passed through a hole 102 a in a side plate 102 of onesegment 1 and brought in contact with the internal plate 106, and thebolt 13 is screwed into the nut 12 as shown in FIG. 5 a. The nut 12 isthen fastened to the internal plate 106 so as to be fixed to the segment1 as shown in FIG. 5 b. The nuts 12 may be fixed to the segments 1 afterthe segments 1 are linked in the circumferential direction as shown inFIG. 3, or the segments may be linked in the circumferential directionso as to constitute the pipe unit 10 after the nuts 12 are first fixedto the segments 1.

A. nut 12 is passed through a hole 103 a in a side plate 103 of anothersegment 1 as shown in FIGS. 5 c and 5 d in order to bring the twosegments 1 together. In this state, the screw member 11 is passedthrough the hole 102 a in the side plate 102 of the segment 1, the holes106 a in the internal plates 106, and the grooves 107 a in the internalplates 107 as shown in FIGS. 4 and 5 e, and the screw 11 b is threadedthrough the nut 12 fixed to one segment 1. The screw member 11 and thenut 12 are thereby linked together. The nut 14 is then threaded untilthe flange 14 a of the nut 14 is pressed against the internal plate 106as shown in FIG. 5 f. This enables the two segments 1, 1 to be fastenedtogether and fixed in place.

In FIG. 4, the linking of segments in the circumferential direction isaccomplished via one set of bolts and nuts, and one bolt 6 is shown inFIG. 4.

A rehabilitating pipe 8 can be assembled inside an existing pipe 9 asshown in FIG. 18 by linking the segments of the pipe unit in the pipelength direction in the manner described above. Grout or another type offiller 8′ is filled in the gap between the existing pipe 9 and therehabilitating pipe 8 to integrate the existing pipe 9 andrehabilitating pipe 8 and construct a composite pipe.

In FIG. 18, the structures of the segments 1 and their linking in thecircumferential direction and pipe length direction would complicate thedrawing and are therefore omitted. In FIG. 18, linked portions 1 abetween segments 1 in the circumferential direction are offset by apredetermined amount in the circumferential direction from linkedportions 1 a of segments adjacent in the pipe length direction. There isnone of such offsets in the example in FIG. 4.

In the embodiment as described above, the width (D in FIG. 3) of asegment 1 in the pipe length direction is constant. This means that thesegment 1 can be said to be a fixed-width segment. On the other hand,FIG. 6 shows a segment whose width can be varied in the pipe lengthdirection of the segment (hereinafter referred to as a variable-widthsegment). FIGS. 6 a through 6 c are cross-sectional views when avariable-width segment is cut in the diametral direction, and FIG. 6 dis an end surface view showing an end plate of a variable-width segment.

A variable-width segment 2 is composed of first and second segmenthalves 3, 4, and a braking rubber 5 is attached as a braking memberbetween the segment halves 3, 4.

The segment half 3 is configured from an internal surface plate 301, aconvex plate 302, a side plate 303, internal plates 304, 305, an endplate 306, and other components, wherein the plates 301 to 306 are allintegrally molded using the same plastic material as the segment 1. Theconvex plate 302 extends parallel to and at a different height from theinternal surface plate 301. The side plate 303, internal plates 304,305, and end plate 306 extend perpendicular to the internal surfaceplate 301.

Recesses 301 a, 301 b are formed on both sides of the internal surfaceplate 301, and a ridge 302 a is formed on the side of the convex plate302 facing the segment half 4. A linking hole 303 a is formed in theside plate 303.

The braking rubber 5 has a belt shape of a predetermined width W1 andpredetermined thickness T1 as shown in FIG. 12 a, and has a lengthcorresponding to the entire circumferential length of the segment half3. The braking rubber 5 is held between the ridge 302 a of the convexplate 302 and the internal plate 305. The braking rubber 5 may also be abelt-shaped braking member composed of plastic or another elasticmaterial other than rubber.

The segment half 4 is configured from an internal surface plate 401, aside plate 403, internal plates 402, 404, 405, an end plate 406, andother components. The plates 401 through 406 are all integrally moldedusing the same plastic material as the segment 1. The side plate 403,the internal plates 404, 405, and the end plate 406 extend perpendicularto the internal surface plate 401, and the internal plate 402 extendsparallel to the internal surface plate 401. A ridge 401 a for fittingwith the recess 301 b of the segment half 3 is formed on the side of theinternal surface plate 401 near the segment half 3, and on the oppositeside a ridge 401 b is formed. In the side plate 403 is formed aprotuberance 403 a for fitting with the holes 102 a, 103 a in the sideplates 102, 103 of the segment 1, or with the hole 303 a in the segmenthalf 3.

A concavity 407 for fitting with the braking rubber 5 and the convexplate 302 of the segment half 3 is formed by the internal plates 402,405 and the internal surface plate 401. The dimensions of these membersare set so that a gap of a small interval D1 is formed between theinternal surface plate 401 and the convex plate 302, and a gap of asmall interval D2 is also formed between the braking rubber 5 and theinternal plate 402, as shown FIG. 7 a. These settings make it possibleto smoothly insert the braking rubber 5 and the convex plate 302 of thesegment half 3 into the concavity 407 of the segment half 4 withoutapplying a load to any of the members, as shown by the arrows in FIGS. 6a and 6 b.

The convex plate 302 and the braking rubber 5 are inserted and fitteddeep into the concavity 407 as shown in FIG. 6 c. The distal end of thebraking rubber 5 comes in contact with an inclined surface 402 a of theinternal plate 402, as shown in FIG. 7 b. When a low-viscosity adhesive5′ is thinly applied in advance over the inclined surface 402 a and alevel surface 402 b of the internal plate 402, the braking rubber 5 canbe fixed to the internal plate 402 of the segment half 4. Since thebraking rubber 5 is held between the internal plate 305 and the ridge302 a of the convex plate 302, the braking rubber 5 and the segment half3 do not move relative to each other and the segment halves 3, 4 remainintegrally coupled via the braking rubber 5 in the state shown in FIG. 6c, as long as no strong force is applied. At this time, the ridge 401 aof the internal surface plate 401 and the recess 301 b of the internalsurface plate 301 are fitted together, and the internal surface plate301 of the segment half 3 and the internal surface plate 401 of thesegment half 4 constitute an even surface wherein the top surface inFIG. 6 has no height differences.

The variable-width segment 2 in the state shown in FIGS. 6 c and 6 d hasthe same shape and structure as the fixed-width segment 1 such as isshown in FIG. 1. The internal surface plates 301 and 401 of thevariable-width segment 2 correspond to the internal surface plate 101 ofthe fixed-width segment 1 and constitute an even internal surface whenthe rehabilitating pipe has been assembled. The side plates 303, 403 ofthe variable-width segment 2 correspond to the side plates 102, 103 ofthe fixed-width segment 1, and the internal plates 304, 404 correspondto the internal plates 106 and reinforce the strength of thevariable-width segment 2. A plurality of holes 303 a of the side plate303 and protuberances 403 a of the side plate 403 are provided accordingto the number of holes 102 a, 103 a formed in the side plates 102, 103of the segment 1.

The width D′ of the variable-width segment 2 in the pipe lengthdirection is the same as the width D (FIG. 3) of the fixed-width segment1, and the arcuate shape of the variable-width segment 2 is an arcuateshape of 72° divided circumferentially into five equal parts, as is thearcuate shape of the fixed-width segment 1. Therefore, the shapes of theside plates 303, 403 of the variable-width segment 2 coincide with thoseof the side plates 102, 103 of the fixed-width segment 1, and all of theplates 301, 302, 304, 305, 401, 402, 404, 405 of the variable-widthsegment 2 as well as the braking rubber 5 and other components have anarcuate shape of 72° divided circumferentially into five equal parts.The braking rubber 5 can also be a ring-shaped endless belt rather thana segment shape.

Watertightness can be increased by applying a seal material in advanceover the internal surfaces of the concavity 407 of the variable-widthsegment 2 and the top surface as seen in FIG. 6 of the convex plate 302.The braking rubber 5 fixed to the internal plate 402 also fulfills asealing function due to the adhesive 5′.

The linking of variable-width segments 2 in the circumferentialdirection is accomplished in the same manner as the linking of segments1 in the circumferential direction; i.e., in the manner as shown in FIG.2. In other words, two variable-width segments 2 are linked in thecircumferential direction by joining the end plates 306, 406 together,passing bolts through the holes 306 a, 406 a (FIG. 6 d) formed in theend plates 306, 406, and fastening the two end plates of the twosegments 2 together with bolts and nuts. Thus, variable-width segmentsare linked sequentially in the circumferential direction, and a pipeunit 20 composed of variable-width segments 2 is assembled (FIG. 10).

FIGS. 8 and 9 show a state in which fixed-width segments 1 are linked inthe pipe length direction via the variable-width segment 2. In FIG. 8,the variable-width segment 2 and a fixed-width segment 1 on the rightside thereof are linked together by fixing a male linking tool 16 intothe hole 103 a in the side plate 103 of the fixed-width segment 1,passing the male linking tool 16 through the hole 303 a in the sideplate 303 of the variable-width segment 2, and snap-fitting the malelinking tool 16 into a female linking tool 17 fixed in the side plate303 of the variable-width segment 2. The variable-width segment 2 and afixed-width segment 1 on the left side thereof are linked together bypress-fitting the protuberance 403 a of the variable-width segment 2into the hole 102 a of the side plate 102 of the fixed-width segment 1.Though not shown in the drawing, nuts 12 such as those shown in FIGS. 4and 5 may also be fixed to the variable-width segment 2, and thevariable-width segment 2 and fixed-width segment 1 on the left side maybe linked together by screw members 11 threaded with the nuts 12.

Thus, the variable-width segment 2 can be linked between the twofixed-width segments 1, 1. The segments 1, 2 are linked in the pipelength direction to assemble the rehabilitating pipe 8 so that the pipeunits 20 composed of variable-width segments 2 are positioned inportions facing the seams 9 a of the existing pipe 9, and the pipe units10 composed of fixed-width segments 1 are positioned in the otherportions, as shown in FIGS. 8 through 10. After the rehabilitating pipe8 is finished being assembled, mortar or another filler 8′ that beginsas a liquid and cures over time is filled in the gap between theexternal periphery of the rehabilitating pipe 8 and the internalperiphery of the existing pipe 9, as was described in relation to FIG.18. The curing of the filler that has been filled in causes therehabilitating pipe 8 to be integrated with the existing pipe 9 via thefiller, thus constructing a strong, rehabilitated composite pipe.

Since the pipe units 20 composed of variable-width segments 2 aredisposed in portions facing the seams 9 a of the existing pipe 9, theperformance of the composite pipe can be improved as describedhereinafter.

In the state shown in FIG. 8, a large amount of tension acts externallyon the existing pipe 9 due to an earthquake or the like, and the seams 9a of the existing pipe 9 separate as shown in FIG. 11. Tension causingthe segment halves 3, 4 to separate also acts on the variable-widthsegments 2 integrated via the filler (not shown) with the existing pipe9. When this tension reaches a predetermined value or greater, thesegment halves 3, 4 also separate as shown in FIG. 11, at which time theridge 302 a of the convex plate 302 digs into the braking rubber 5 at adepth T2 about ⅓ of the thickness T1 of the braking rubber 5,elastically deforming the braking rubber 5 as shown in FIG. 12 b. Theridge 302 a of the convex plate 302 digging into the braking rubber 5brakes the segment halves 3, 4 from pulling apart. However, if thetension is greater than this braking force, the segment halves 3, 4 moverelative to each other by a distance corresponding to the amount bywhich the seams 9 a have separated, and the pipe length of the pipe unit20 is elongated.

Even if the segment halves 3, 4 move relative to each other in thedirection in which they would separate, the rehabilitating pipe 8remains contiguous as long as the ridge 302 a of the convex plate 302digs into the braking rubber 5, and even if the seams 9 a of theexisting pipe 9 separate, liquefied sand or the like can be preventedfrom flowing into the rehabilitating pipe 8 from these portions 9 a,thus improving the earthquake resistance of the pipe.

FIGS. 13 and 14 show an embodiment in which variable-width segments 2are disposed in the curved locations of an existing pipe so as toassemble a curved rehabilitating pipe.

Pipe units 20 composed of variable-width segments 2 are linked betweenpipe units 10 composed of three fixed-width segments 1 in accordancewith the curvature of the existing pipe in order to assemble a curvedrehabilitating pipe 8 as shown in FIG. 13.

In FIG. 13, the dimension of each pipe unit 10 in the pipe lengthdirection, i.e., the width of each fixed-width segment 1 in the pipelength direction is denoted by D (FIG. 3), and the width in the pipelength direction of each variable-width segment 2 shown in FIG. 6 c isalso D (=D′). The width D of the variable-width segment 2 in the pipelength direction can be varied by spreading the segment halves 3, 4relative to each other in the form of a fan. For example, when thesegment halves 3, 4 of the variable-width segment 2 are relativelyspread in the pipe length direction from the state shown in FIG. 14 b tothe state in FIG. 14 a, the ridge 302 a of the convex plate 302 moves byan amount a in the pipe length direction, and the width in the pipelength direction of the variable-width segment 2 in this spread portionbecomes D+α. This also causes the ridge 401 a of the internal surfaceplate 401 and the recess 301 b of the internal surface plate 301 to beangled and widened by an amount θ1.

This spread amount (a) of the segment halves 3, 4 of the variable-widthsegments 2 can be adjusted at the circumferential position of eachsegment. Therefore, the widths of the variable-width segments 2 arecontinuously varied as shown in FIG. 13 so that the spread amountincreases progressively from one side to the other along thecircumferential direction of the rehabilitating pipe 8 (from the bottomto the top in FIG. 13). Specifically, the widths of the variable-widthsegments 2 in the pipe length direction are continuously varied so as tobe at a minimum in the internal periphery of the curved portions (nospread or offset in FIG. 14 b) and a maximum spread (a) in the externalperiphery of the curved portions (the top position as seen in thediametral direction in FIG. 14 a). By continuously varying the segmentwidth in this manner, the pipe units 20 can be curved at an angle θ1,and the rehabilitating pipe 8 can be curved at an angle θ1.

Even if the angle θ1 of curvature in one pipe unit 20 is small, theangle of curvature of the entire rehabilitating pipe 8 can be increasedby linking pipe units 20 at a plurality of locations. The variable-widthsegment 2 used in the present embodiment is preferably one having asmall circumferential length, i.e., one having a length resulting fromdividing the rehabilitating pipe 8 circumferentially into numerous equalparts (for example, eight or more equal parts). This is to ensure thatthe amount of spread described above can be reasonably increasedcontinuously in the variable-width segments 2 of the pipe units 20.

Even if the amount of spread is varied as described above, thevariable-width segments 2 can be linked in the circumferential directionby the method described above, i.e., by using bolts and nuts, becausethe end plates 306, 406 of variable-width segments 2 adjacent in thecircumferential direction are parallel and of the same size. As forlinking in the pipe length direction, variable-width segments can belinked to each other by fitting protuberances 403 a of side plates 403into holes 303 a of adjacent side plates 303, and variable-widthsegments 2 and fixed-width segments 1 can be linked together in themanner shown in FIG. 8.

Though not shown in the drawings, also in this embodiment, the gapbetween the internal periphery of the existing pipe and the externalperiphery of the rehabilitating pipe 8 is filled with a filler after therehabilitating pipe 8 is assembled inside the existing pipe. Thus, theexisting pipe and rehabilitating pipe are integrated, forming acomposite pipe in the same manner as is described above.

According to the present embodiment, a curved rehabilitating pipe 8 canbe assembled merely by linking pipe units 20 composed of variable-widthsegments 2 at portions which will be curved and adjusting the widths ofthe variable-width segments 2 of the pipe units 20 as described above.Therefore, a curved rehabilitating pipe can be assembled in a simplemanner in a short amount of time without the need for special machiningof the segments at a work site.

Since the variable-width segments 2 expand and contract in the widthdirection as in the embodiment in FIGS. 6 through 11, the curvedrehabilitating pipe is prevented from rupturing in the portions of thevariable-width segments 2 even if an external force acts from theexterior due to an earthquake or the like.

In the case that the rehabilitating pipe does not require earthquakeresistance, the braking rubber 5 can be omitted as shown in FIGS. 15 athrough 15 d.

In FIGS. 15 a through 15 d, components identical to those in FIGS. 6 athrough 6 d are denoted by the same numerical symbols and are notdescribed in detail. A convex plate 302′ of the segment half 3corresponds to the convex plate 302 in FIGS. 6 a through 6 d, and theridge 302 a′ of the convex plate 302′ formed at the distal end is longerin the diametral direction in comparison with FIGS. 6 a through 6 d. Aninternal plate 402′ of the segment half 4 corresponds to the internalplate 402 in FIGS. 6 a through 6 d, but unlike FIGS. 6 a through 6 d,there is no inclined surface and a level surface 402 a′ is formed.

The ridge 302 a′ of the convex plate 302′ has a diametral length suchthat the ridge 302 a′ can be inserted with room to spare into theconcavity 407 of the segment half 4. The convex plate 302′ of thesegment half 3 is fitted into the concavity 407 of the segment half 4 asshown in FIGS. 15 a and 15 b, and a variable-width segment 2′ having norubber stop is formed as shown in FIG. 15 c.

Such variable-width segments 2′ are also linked in both thecircumferential direction and pipe length direction, as are thevariable-width segments 2 shown in FIGS. 6 a through 6 d, and are usedin the assembly of a curved rehabilitating pipe by the same method aswas described in connection with FIG. 13.

The variable-width segments are integrated and fixed in place by thefiller (mortar or the like) filled in between the existing pipe and therehabilitating pipe. Therefore, the segment halves 3, 4 do notnecessarily need to be fitted and linked together as shown in FIGS. 15 athrough 15 d. Segment halves can also be superposed so as to constitutea variable-width segment as shown in FIGS. 16 a through 16 d.

In FIGS. 16 a through 16 d, a segment half 50 is comprised of aninternal surface plate 501 corresponding to the internal surface plate301 in FIGS. 15 a through 15 d, a convex plate 502 corresponding to theconvex plate 302′, a side plate 503 corresponding to the side plate 303,internal plates 504, 505 corresponding to the internal plates 304, 305,an end plate 506 corresponding to the end plate 306, and the like. Theplates 501 through 506 are all integrally molded using the same plasticmaterial as the segment 1. The convex plate 502 extends parallel to theinternal surface plate 501 at a different height therefrom, and the sideplate 503, internal plates 504, 505, and end plate 506 extendperpendicular to the internal surface plate 501.

A ridge 501 a and a ledge 501 b are formed on one and the other side ofthe internal surface plate 501, and a ridge 502 a is formed on the sideof the convex plate 502 facing a segment half 60. A hole 503 a is formedin the side plate 503.

The segment half 60 is composed of an internal surface plate 601corresponding to the internal surface plate 401, a side plate 603corresponding to the side plate 403, internal plates 604, 605corresponding to the internal plates 404, 405, an end plate 606corresponding to the end plate 406, and other components. The plates 601through 606 are all integrally molded using the same plastic material asthe segment 1. The side plate 603, the internal plates 604, 605, and theend plate 606 extend perpendicular to the internal surface plate 601. Arecess 601 a for fitting with the ridge 501 a of the segment half 50 isformed in the internal surface plate 601 on the side opposite thesegment half 50, and a concavity 601 b through which the ridge 502 a ofthe convex plate 502 slides is formed in the circumferential directionon the bottom surface of the internal surface plate 601. Formed in theside plate 603 is a protuberance 603 a for fitting with the holes 102 a,103 a in the side plates 102, 103 of the segment 1, or with the hole 503a in the segment half 50. Holes 506 a, 606 a for linking segments in thecircumferential direction are formed in the end plates 506, 606.

The segment halves 50, 60 configured in this manner are moved so thatthe convex plate 502 of the segment half 50 and the internal surfaceplate 601 of the segment half 60 are made to overlap by sliding theridge 502 a of the convex plate 502 through the concavity 601 b of thesegment half 60, as shown in FIGS. 16 a and 16 b. The segment halves 50,60 are moved relative to each other until reaching the state in FIG. 16c in which the distal end of the internal surface plate 601 comes incontact with the ledge 501 b of the internal surface plate 501 and theridge 502 a of the convex plate 502 comes in contact with the internalplate 605. Thus, a variable-width segment 40 is formed having a width ofD′ in the pipe length direction. At this time, the internal surfaceplate 501 of the segment half 50 and the internal surface plate 601 ofthe segment half 60 are coplanar.

Variable-width segments 40 can also be linked in the circumferentialdirection and pipe length direction, similar to the variable-widthsegments 2, 2′, and the widths in the pipe length direction can beadjusted at the circumferential position of each segment. Therefore, apipe unit 41 composed of variable-width segments 40 can be assembled bythe same method as is shown in FIG. 13, and the widths of thevariable-width segments 40 can be continuously increased progressivelyfrom one side to the other along the circumferential direction of therehabilitating pipe 8. Thus, the widths of the variable-width segments40 can be continuously varied from D to D+α, and the rehabilitating pipe8 can be curved at an angle θ1, as shown in FIG. 17.

Since the segment halves 50, 60 are merely superposed together, there isa danger of them moving in the diametral direction and separating.Therefore, after the positions of the segments are adjusted in the widthdirection, the segment halves 50, 60 are preferably temporarily bondedor temporarily joined in a superposed state. When the existing pipe andrehabilitating pipe are integrated by the filler filled in between thetwo, the segment halves 50, 60 can no longer move, and accordingly thereis no danger of the segment halves moving in the diametral direction.

The same effects can be achieved with the variable-width segment 40 aswith the variable-width segment 2′, and the advantage of thevariable-width segment 40 is that the segment structure can be madesimpler than with the variable-width segment 2′.

What is claimed is:
 1. An existing pipe rehabilitation method forrehabilitating an existing pipe by linking segments in thecircumferential and pipe length directions to assemble a rehabilitatingpipe inside the existing pipe, the segments each including an internalsurface plate, side plates that are erected vertically at both sidesextending in the circumferential direction of the internal surfaceplate, and a plurality of internal plates that are erected on the topsurface of the internal surface plate, and the segments being linked inthe pipe length direction by the following steps: securing a pluralityof nuts along the circumferential direction to the internal plate ofeach segment that lies in a position nearest to the side plate thereof;preparing a fastening member that can be screwed into the nut; abuttingfirst and second segments and screwing the fastening member into the nutto fasten the first and second segments for linkage in the pipe lengthdirection thereof; and sequentially liking the segments to the linkedsegments by the fastening member.
 2. An existing pipe rehabilitationmethod according to claim 1, wherein the fastening member is screwedfrom the internal plate of the first segment into the nut secured to thesecond segment, thereby bringing the other end of the fastening memberon the side opposite to the nut into pressing contact with the internalplate so as to fasten the first and second segments in the pipe lengthdirection.
 3. An existing pipe rehabilitation method according to claim2, wherein the internal plate with which the fastening member makespressing contact is the internal plate furthest from the nut into whichthe fastening member is screwed.
 4. An existing pipe rehabilitationmethod according to claim 1, wherein the nut extends in the pipe lengthdirection so long as to protrude to the exterior of the side plate ofthe second segment in a state in which the nut is secured to theinternal plate thereof, and the protruding distance is equal to orgreater than the thickness of the side plate of the first segment towhich the second segment is linked.
 5. An existing pipe rehabilitationmethod according to claim 1, wherein the nut position in the segment isoffset as viewed in the circumferential direction from the nut positionof the adjacent segments.
 6. An existing pipe rehabilitation methodaccording to claim 1, wherein the fastening member is a screw memberhaving at one end a screw part that is screwed into the nut secured tothe segment, and at the other end a screw part on which another nut ismounted.
 7. An existing pipe rehabilitation method according to claim 1,wherein the fastening member is a bolt.